Conveyor chains 10 (FIGS. 11-14) are ordinarily fabricated of male and female links 12, 14 pivotally interconnected to form a flexible but sturdy construction. These chains are generally attached to transport elements, such as flights (FIG. 15), to transport products in a manufacturing process. In use the chains are wrapped about a plurality of sprockets, at least one of which is driven, and passed along a prescribed circuit.
The female link 14 (FIGS. 11-14) is typically formed as a unitary cast or fabricated member having a central bar segment 16 and a pair of bifurcated ends 18. The bar segment has a rectangular cross-sectional shape. Each end 18 forms a pair of arms 20 which are spaced apart to define a gap 22 therebetween. Each of the arms 20 further defines a transverse bore 24, such that the bores 24 of opposed arms are aligned with one another. The inner sides 26 of the arms generally have a planar shape for matingly receiving a male link 12. The outer sides 28 are each provided with a pair of spaced apart stops 30. The stops are positioned to each side of bore 24 to form an elongated channel 32 therebetween which intersects the bore. The channels 32 are provided to receive and retain a T-head 34 of a bolt 36 to prevent the bolt's rotation. Stops 30 are provided on the outer side of each arm 20 so that female links 14 may be assembled into the chain without concern for their particular orientation.
Male link 12 (FIGS. 11-14) is also typically formed as a unitary cast or fabricated member. The male link has a generally rectangular parallelepiped shape across its entire length. The width of link 12 is substantially equal to the size of gap 22 so that the link may be matingly received within the gap. Specifically, the ends 38 of male links 12 are received for free pivotal movement in gaps 22 of adjacent female links 14 to enable the chain to possess the requisite flexibility. Each end 38 further defines a transverse bore 39 which is aligned with a pair of the opposed bores 24 in female link 14. The shank 42 of bolt 36 is passed through the aligned bores 24, 39 to pivotally couple links 12 and 14 together. However, in view of the large stresses placed on the chain, the bores are often subject to premature wearing and failure.
In the assembled chain, bolts 36 are positioned through bores 24, 39 such that T-head 34 is matingly received within channel 32. A spacer 40 is passed over the free end of threaded shank 42 in order to provide a flat surface 44 of ample size for nut 46 to abut. More specifically, spacer 40 is a cylindrical disk member which includes a pair of shoulders 48. The shoulders are adapted to be matingly received in the outer portions of channel 32 and thereby function to stabilize and support the spacer.
As an example, conveyor chains 10 have been used in low-flow baths 50 to separate refuse 52 from coal 54 to upgrade the quality of the coal (FIG. 10). In general, bath 50 includes a tank 56 partially filled with a fluid media 58, such as water mixed with a finely ground magnetite. The concentration of the magnetite is selected so that when the raw coal is deposited in the tank, the coal floats but the refuse sinks. A conveyor chain 10 is employed to separately remove both the coal and refuse from the tank.
In this environment, elongate flights 60 are secured between a pair of parallel chains 10 (FIGS. 12 and 15). A flight 60 is comprised of an elongated body 62 provided with an orthogonal foot 64 at each end. The body 62 is a thin member having a relatively wide working face 65. Feet 64 ordinarily extend outward from body 62 to define the flight in a generally I-shaped configuration. Each foot 64 defines a pair of spaced apart holes 66, which are adapted to be received over the free ends of adjacent bolts 36. In this construction, feet 64 of flights 60 are sandwiched between spacers 40 and nuts 46. Body 62 spans the space between the two chains 10 such that the working face 65 is placed upright (i.e., perpendicular to the direction of chain travel).
In the operation of bath 50, the raw coal is dumped into the tank via feed chute 78 (FIG. 10). Once in the fluid media, the raw coal separates (because of the different specific gravities of the materials) such that the coal floats on the surface 79 of media 58 while the refuse sinks to the bottom 80 of the tank. The floating coal is skimmed out of the tank by flights 60 passing along the upper path 81 of the chain circuit. The flights drive the coal up out of the fluid media along ramp 82, over the end of the tank and into clean coal chute 84. Similarly, flights 60 pass along the lower path 85 of the circuit at the bottom 80 of the tank to push the refuse toward sprocket 68a. At the end of the tank, the refuse is dropped into the refuse chute 86 as the chains rotate around sprocket 68a.
The chains 10 in bath 50 (FIG. 10) are passed along a defined path which extends around sprockets 68a, 68b, at least one of which is driven by a motor (not shown). In between the sprockets 68a, 68b, the chains are received into slots 70 defined by wear and guide rails 74a, 74b attached to the sides 72 of tank 56 (FIG. 15). Rails 74a, 74b define opposed engagement faces 76a, 76b to form the slots 70. The slots cause the chains to follow a non-linear path designed to remove the refuse and coal from the tank. Due to the weight of the chains 10 and flights 60, the lower sides of links 12, 14 generally slide along face 76b of the lower wear rail 74b. As to be expected, this sliding causes links 12, 14 to be quickly worn away.